On numerical estimates of the parameters of localized plasticity during metal tension

The article considers the results of a study of the nature and quantitative characteristics of localized plastic flow of metals under uniaxial tension using speckle photography method.
It has been revealed that, in the solid bodies, plastic deformation tends to localize on the macro-scale level ranging from the yield stress to the failure.
Localization phenomenon represents a spontaneous layering of the material into non-deforming and actively deforming volumes, which are arranged over the test sample in the form of specified patterns. Each pattern transforms consistently in accordance with a plastic flow development. Moreover, the patterns are defined by the law of strain hardening acting at the given stage of plastic flow. The patterns appear in the following order: (i) switching autowave; (ii) phase autowaves; and (iii) stationary dissipative structures. At the pre-fracture stage, the collapse of autowaves is observed.
A quantitative analysis of the results obtained has been carried out. The elastoplastic strain invariant has been determined experimentally. The nature of this invariant has been also discussed. According to the latter, development of the plastic deformation occurs due to autowave processes of localized plasticity that, in turn, depends on the elastic deformation. Hence, both types of deformation are interdependent and defined by the plastic flow diagram. It has been demonstrated that a theoretical simulation can be used to predict the parameters of autowaves of localized plastic flow in deformable alloys. In the considered approach, the plastic deformation is regarded as a result of self-organization process, which occurs in an active deformed system with nonlinear structural defects.